Since we didn't check and insist that args.pad must be zero for MMAP_GTT historically, we cannot insert a check now as old userspace may be feeding in garbage. As such the lack of check is enshrined into the ABI, so add a comment to remind us we cannot add the check later.
Signed-off-by: Chris Wilson <[email protected]> Cc: Joonas Lahtinen <[email protected]> --- drivers/gpu/drm/i915/gem/i915_gem_mman.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c index 3a3f30bc8ac7..15faf95d74ca 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c @@ -620,6 +620,15 @@ i915_gem_mmap_offset_ioctl(struct drm_device *dev, void *data, enum i915_mmap_type type; int err; + /* + * Historically we failed to check args.pad and args.offset + * and so we cannot those fields for user input and we cannot + * add -EINVAL for them as the ABI is fixed, i.e. old userspace + * may be feeding in garbage in those fields. + * + * if (args->pad) return -EINVAL; is verbotten! + */ + err = i915_user_extensions(u64_to_user_ptr(args->extensions), NULL, 0, NULL); if (err) -- 2.24.0 _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
